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# Perfect Ellipse?

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dery
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Post Options    Thanks(0)    Quote  Reply Topic: Perfect Ellipse?
Posted: 29.May.2023 at 19:34
Can someone please tell me what is perfect ellipse and how do I draw it in AutoCAD 2014?

Thanks
TECH 011
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Post Options    Thanks(0)    Quote  Reply Posted: 30.May.2023 at 08:18
I also want to know the answee
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Arkance Systems CZ

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Post Options    Thanks(0)    Quote  Reply Posted: 30.May.2023 at 08:26
Perfect true (B-rep) ellipse can be created with the ELLIPSE command (with the PELLIPSE setting kept on 0).
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dery
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Post Options    Thanks(0)    Quote  Reply Posted: 30.May.2023 at 11:30
What is perfect ellipse? Can anyone show me easy example of how to construct perfect ellipse using technical drawing method in AutoCAD?
Kent Cooper
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Post Options    Thanks(0)    Quote  Reply Posted: 30.May.2023 at 14:37
dery wrote:  Can anyone show me easy example of how to construct perfect ellipse using technical drawing method in AutoCAD?

Use the ELLIPSE command [with the PELLIPSE System Variable set to 0].  If you want to do it with the electronic equivalent of manual drafting techniques, using something like a compass, you can't make it a true elliptical shape, because the curvature of an ellipse is of constantly changing radius, so there's nowhere to put the compass point.  If PELLIPSE is set to 1, it makes an approximation with 16 arc segments, which is pretty close [and was the only way, and that System Variable did not exist, in early versions before the ELLIPSE command made a real elliptical shape].

Edited by Kent Cooper - 30.May.2023 at 14:44
dery
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Post Options    Thanks(0)    Quote  Reply Posted: 30.May.2023 at 15:26
What is the difference between a perfect ellipse and regular ellipse?
philippe JOSEPH
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Post Options    Thanks(0)    Quote  Reply Posted: 31.May.2023 at 08:00
Hello dery and Kent, in fact the actual ellipse command is very good within the limitation of it being with facets but very precise anyway.
Before AutoCAD R13 of year 1995 ! the R 12 release had effectively not so precise ellispses and as R12 was the first software coming in my work company this lead to a funny exchange between an old but reliable engineer with "only" his polish method calculator and an young with no experience contractor unable to draw "perfect" ellipses with the R12, only given the OK with the R13 release.
Dery, up to what level of perfection do you want to go ?
I once complained about the unprecise helix drawn by AutoCAD and a german guy gave me a program to draw it correctly because the AutoCAD one was 200 mm apart ( only at the extremities ) for a 10 m radius.
dery
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Post Options    Thanks(0)    Quote  Reply Posted: 31.May.2023 at 10:37
 philippe JOSEPH wrote:Hello dery and Kent, in fact the actual ellipse command is very good within the limitation of it being with facets but very precise anyway.Before AutoCAD R13 of year 1995 ! the R 12 release had effectively not so precise ellispses and as R12 was the first software coming in my work company this lead to a funny exchange between an old but reliable engineer with "only" his polish method calculator and an young with no experience contractor unable to draw "perfect" ellipses with the R12, only given the OK with the R13 release.Dery, up to what level of perfection do you want to go ?I once complained about the unprecise helix drawn by AutoCAD and a german guy gave me a program to draw it correctly because the AutoCAD one was 200 mm apart ( only at the extremities ) for a 10 m radius.

Why do you ask "Dery, up to what level of perfection do you want to go ?"?

I have no idea what you're talking about.
philippe JOSEPH
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Post Options    Thanks(0)    Quote  Reply Posted: 31.May.2023 at 11:07
Dery, how much precise must be your ellipse and for what use do you want a perfect ellipse ?
dery
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Post Options    Thanks(0)    Quote  Reply Posted: 31.May.2023 at 20:33
 philippe JOSEPH wrote:Dery, how much precise must be your ellipse and for what use do you want a perfect ellipse ?

Does perfect ellipse availble in precise and unprecise?

If so, I choose precise.

Please show me how to construct perfect ellipse using technical drawing method in AutoCAD.

Edited by dery - 31.May.2023 at 20:35